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Near infrared-emitting tris-bidentate Os(II) phosphors: control of excited state characteristics and fabrication of OLEDs

Liao, J.-L.; Chi, Y.; Yeh, C.-C.; Kao, H.-C.; Chang, C.-H.; Fox, M.A.; Low, P.J.; Lee, G.-H.

Near infrared-emitting tris-bidentate Os(II) phosphors: control of excited state characteristics and fabrication of OLEDs Thumbnail


Authors

J.-L. Liao

Y. Chi

C.-C. Yeh

H.-C. Kao

C.-H. Chang

P.J. Low

G.-H. Lee



Abstract

A series of four Os(II) complexes bearing (i) chromophoric diimine ligands (N^N), such as 2,2′-bipyridine (bpy) and substituted 1,10-phenanthrolines, (ii) dianionic bipz chelate ligands derived from 5,5′-di(trifluoromethyl)-2H,2′H-3,3′-bipyrazole (bipzH2), and (iii) bis(phospholano)benzene (pp2b) as the third ancillary ligand completing the coordination sphere were synthesized. X-ray diffraction studies confirm the heteroleptic tris-bidentate coordination mode. These Os(II) complexes [Os(N^N)(bipz)(pp2b)], N^N = bpy (3), phenanthroline (4), 3,4,7,8-tetramethyl-1,10-phenanthroline (5) and 4,7-diphenyl-1,10-phenanthroline (6), display near infrared (NIR) emission between 717 nm and 779 nm in the solid state at RT. On the basis of hybrid-DFT and TD-DFT calculations, the emissions are assigned to metal-to-ligand charge transfer transitions (3MLCT) admixed with small ligand-to-ligand charge transfer (3LLCT) contributions. Successful fabrication of organic light emitting diodes (OLEDs) using Os(II) complex 5 as the dopant and either tris(8-hydroxyquinoline) aluminum (Alq3) or 3,3′,5,5′-tetra[(m-pyridyl)-phen-3-yl]-biphenyl (BP4mPy) as the host is reported. These OLEDs were measured with emission maxima at 690 nm and extending into the NIR, with peak power efficiencies of up to 0.13 lm W−1 and external quantum efficiencies of up to 2.27%.

Citation

Liao, J., Chi, Y., Yeh, C., Kao, H., Chang, C., Fox, M., …Lee, G. (2015). Near infrared-emitting tris-bidentate Os(II) phosphors: control of excited state characteristics and fabrication of OLEDs. Journal of Materials Chemistry C Materials for optical and electronic devices, 3(19), 4910-4920. https://doi.org/10.1039/c5tc00204d

Journal Article Type Article
Acceptance Date Apr 11, 2015
Publication Date May 21, 2015
Deposit Date Apr 30, 2015
Publicly Available Date Mar 29, 2024
Journal Journal of Materials Chemistry C Materials for optical and electronic devices
Print ISSN 2050-7526
Electronic ISSN 2050-7534
Publisher Royal Society of Chemistry
Peer Reviewed Not Peer Reviewed
Volume 3
Issue 19
Pages 4910-4920
DOI https://doi.org/10.1039/c5tc00204d

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Copyright Statement
This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.





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